When a work piece is to be machined or otherwise operated upon, it is often important that the work piece be held fixed and at a precise position. Commonly a vise is utilized to hold the work in a fixed position relative to machines which operate upon the work, such as a drill or milling machine. The vise typically includes two opposing ends with one of the ends being fixed and the other end adapted to move toward and away from the fixed end. Jaws are typically provided upon these ends with the jaws coming into direct contact with the work being held.
Such standard vises do a particularly good job of supporting the work in a manner resisting motion and properly positioning the work in a vertical direction, due to the base underlying the work; and in a first horizontal direction aligned with a direction that the moving end of the vise moves relative to the fixed end of the vise, through resistance provided directly by the jaws of the vise. However, horizontal motion of the work relative to the vise in a direction lateral to the direction of motion of the ends of the vise is only resisted through friction forces between the work and the jaws. These friction forces vary based on the surface condition of the jaws, the surface condition of the work and the amount of tightening force with which the jaws engage the work. If these friction forces are exceeded by forces applied to the work by a milling machine or other tool, the work will slide within the jaws, potentially destroying the work, damaging the milling machine or other tool, or otherwise providing negative results. Even if the work is held tight, it is difficult to precisely position work pieces in the same desired location reliably, especially in this lateral horizontal direction.
Various attempts have been made in the prior art to provide mechanical stops to support the work laterally, so that a position of the work within the jaw can be held fixed and at a desired location with forces other than merely friction forces. Such prior art attempts are cataloged in the following prior art patents and published applications: Pingel, U.S. Pat. No. 3,810,311; Philipoff, U.S. Pat. No. 4,030,718; Donnelly, U.S. Pat. No. 4,635,912; Adams, U.S. Pat. No. 5,018,562; Ewing, U.S. Pat. No. 5,996,986; Wolfe, U.S. Pat. No. 6,029,967; Wolfe, U.S. Pat. No. 6,217,014; Cairns, U.S. Publication No. 2003/0071404; and Bentley, U.S. Publication No. 2003/0102615.
Many of these prior art mechanical stops attach to the base of the vise, or other structures other than directly to the vise jaws. Such an arrangement is more difficult to calibrate and use on a variety of different machines with which the vise is associated. When such prior art mechanical stops are coupled directly to the vise jaws, themselves, the complexity of the mechanical stops inhibit their use in a quick and convenient fashion.
Additionally, many such devices provide less than fully satisfactory resistance to lateral motion of the work by relying on friction forces to some extent, rather than purely upon the strength of the materials from which the stop is made directly. For instance, the patent to Wolfe (U.S. Pat. No. 6,029,967) provides a sliding stop which resides within a channel in a top of a vise jaw. The sliding stop has a tightening mechanism so that it can be secured at the desired position within the channel. However, this tightening mechanism relies upon friction itself to hold the sliding stop in position. Hence, the risk of sliding of the stop is not entirely alleviated. Additionally, as such tightening mechanisms wear out, the effectiveness of such sliding stops can tend to degrade over time. Additionally, such a sliding stop mechanism and associated channel have a fairly significant degree of complexity, making their convenient use more difficult and resulting in additional cost to manufacture such prior art mechanical stops.
Accordingly, a need exists for a work stop which can be conveniently used with a vise jaw and which can securely hold the work in position relative to the jaw without reliance upon friction forces and which has sufficient simplicity to facilitate convenient use and low cost.